func (this *Geos) PreparedDestroy(geom *PreparedGeom) {
if geom.v != nil {
C.GEOSPreparedGeom_destroy_r(this.v, geom.v)
geom.v = nil
} else {
log.Printf("double free?")
}
}
func cGEOSPreparedGeom_destroy(g *C.GEOSPreparedGeometry) {
handlemu.Lock()
defer handlemu.Unlock()
C.GEOSPreparedGeom_destroy_r(handle, g)
}